static void Main(string[] args)
{
// long i = 500;
Console.WriteLine("begin");
//int num = 1000000;
Console.WriteLine(LatticePaths.Solve(1000, 1000));
}
public void TestOne()
{
Assert.AreEqual(6, LatticePaths.Solution(2));
Assert.AreEqual(20, LatticePaths.Solution(3));
}